<!DOCTYPE HTML>
<html>
<head>
    <meta http-equiv="Content-Type" content="text/html; charset=utf-8">
    <title>运营系统登录页</title>

    <link href="static/css/login.css" rel="stylesheet" type="text/css">
    <script type="text/javascript" src="static/lib/jquery/1.9.1/jquery.min.js"></script>
    <script src="static/js/verificationNumbers.js" tppabs="static/js/verificationNumbers.js"></script>
    <style>
        .J_codeimg{z-index:-1;position:absolute;}
        *{
            margin:0;
            padding:0;
        }
        #demo{
            width:100vw;
            height:100vh;
            position:relative;
        }
        #canvas{
            position:absolute;
            left:0;
            right:0;
            top:0;
            bottom:0;
            z-index: -1;
        }
    </style>

</head>
<body>
<div class="login-box" id="demo">
    <div class="input-content">
        <div class="login_tit">
            <div>
                <i class="tit-bg left"></i>
                Everyday · 运营系统
                <i class="tit-bg right"></i>
            </div>
            <p>Strive&nbsp;&nbsp;&nbsp;&nbsp;Everyday</p>
        </div>
        <p class="p user_icon">
            <input type="text" placeholder="账号" autocomplete="off" class="login_txtbx">
        </p>
        <p class="p pwd_icon">
            <input type="text" placeholder="密码" autocomplete="off" class="login_txtbx">
        </p>
        <div class="p val_icon">
            <div class="checkcode">
                <input type="text" id="J_codetext" placeholder="验证码" autocomplete="off" maxlength="4" class="login_txtbx">
                <canvas class="J_codeimg" id="myCanvas" onclick="createCode()" onselectstart="return false">对不起，您的浏览器不支持canvas，请下载最新版浏览器!</canvas>
            </div>
            <a class="ver_btn" onclick="createCode();" onselectstart="return false">看不清，换一张</a>
        </div>
        <div class="signup">
            <a class="gv" href="#" onclick="validate()">登&nbsp;&nbsp;录</a>
            <a class="gv" href="#">清&nbsp;&nbsp;空</a>
        </div>
    </div>
    <div class="canvaszz"> </div>
    <canvas id="canvas"></canvas>
</div>
<script>
  //宇宙特效
  "use strict";
  let canvas = document.getElementById('canvas'),
    ctx = canvas.getContext('2d'),
    w = canvas.width = window.innerWidth,
    h = canvas.height = window.innerHeight,
    hue = 217,
    stars = [],
    count = 0,
    maxStars = 2500//星星数量

  const canvas2 = document.createElement('canvas'),
    ctx2 = canvas2.getContext('2d')
  canvas2.width = 100;
  canvas2.height = 100;
  const half = canvas2.width / 2,
    gradient2 = ctx2.createRadialGradient(half, half, 0, half, half, half)
  gradient2.addColorStop(0.025, '#CCC');
  gradient2.addColorStop(0.1, 'hsl(' + hue + ', 61%, 33%)');
  gradient2.addColorStop(0.25, 'hsl(' + hue + ', 64%, 6%)');
  gradient2.addColorStop(1, 'transparent');

  ctx2.fillStyle = gradient2;
  ctx2.beginPath();
  ctx2.arc(half, half, half, 0, Math.PI * 2);
  ctx2.fill();

  // End cache

  function random(min, max) {
    if (arguments.length < 2) {
      max = min;
      min = 0;
    }

    if (min > max) {
      const hold = max
      max = min;
      min = hold;
    }

    return Math.floor(Math.random() * (max - min + 1)) + min;
  }

  function maxOrbit(x, y) {
    const max = Math.max(x, y),
      diameter = Math.round(Math.sqrt(max * max + max * max))
    return diameter / 2;
    //星星移动范围，值越大范围越小，
  }

  const Star = function () {

    this.orbitRadius = random(maxOrbit(w, h));
    this.radius = random(60, this.orbitRadius) / 18;
    //星星大小
    this.orbitX = w / 2;
    this.orbitY = h / 2;
    this.timePassed = random(0, maxStars);
    this.speed = random(this.orbitRadius) / 500000;
    //星星移动速度
    this.alpha = random(2, 10) / 10;

    count++;
    stars[count] = this;
  }

  Star.prototype.draw = function() {
    const x = Math.sin(this.timePassed) * this.orbitRadius + this.orbitX,
      y = Math.cos(this.timePassed) * this.orbitRadius + this.orbitY,
      twinkle = random(10)

    if (twinkle === 1 && this.alpha > 0) {
      this.alpha -= 0.05;
    } else if (twinkle === 2 && this.alpha < 1) {
      this.alpha += 0.05;
    }

    ctx.globalAlpha = this.alpha;
    ctx.drawImage(canvas2, x - this.radius / 2, y - this.radius / 2, this.radius, this.radius);
    this.timePassed += this.speed;
  }

  for (let i = 0; i < maxStars; i++) {
    new Star();
  }

  function animation() {
    ctx.globalCompositeOperation = 'source-over';
    ctx.globalAlpha = 0.5; //尾巴
    ctx.fillStyle = 'hsla(' + hue + ', 64%, 6%, 2)';
    ctx.fillRect(0, 0, w, h)

    ctx.globalCompositeOperation = 'lighter';
    let i = 1, l = stars.length
    for (; i < l; i++) {
      stars[i].draw();
    };

    window.requestAnimationFrame(animation);
  }

  animation();
</script>

</body>
</html>
